3-Pin Switch-Mode
LED Lamp Driver IC

The HV9921 is a pulse width modulated (PWM) high-
ef, ciency LED Driver control IC. It allows ef, cient operation of
LED strings from voltage sources ranging up to 400VDC. The
HV9921 includes an internal high voltage switching MOSFET
controlled with , xed off-time (T ) of approximately 10.5s.
OFF
The LED string is driven at constant current, thus providing
constant light output and enhanced reliability. The output
current is internally , xed at 20mA for HV9921. The peak
current control scheme provides good regulation of the output
current throughout the universal AC line voltage range of 85
to 264VAC or DC input voltage of 20 to 400V. By Supertex, Inc.